Memory devices developed based on semiconductor techniques, such as dynamic random access memory (DRAM), static random access memory (SRAM), and non-volatile memory, have taken a major part in today's semiconductor industry. These memories have been broadly applied to personal computers, mobile phones, and networks and have become one of the most indispensable electronic products in our daily life.
The demand to memories having low power consumption, low cost, high access speed, small volume, and high capacity has been increasing drastically along with the widespread of consumable electronic products and system products. Among existing memories, the memory which records data by changing the resistance of a variable-resistance layer is one of the most focused memory devices.
In a resistive random access memory (RRAM), the state of a variable resistance layer is changed by applying a current pulse and a conversion voltage, so as to switch between a set state and a reset state according to different resistances. The digital data “0” and “1” is recorded in the memory according to the set and reset states corresponding to different resistances.